Background:: Low back disorder is the most common problem in the entire spinal axis. About two-thirds of adults suffer from low back pain (LBP) at some time. Pain generators in the lumbar spine include the annulus of the disc, the posterior longitudinal ligament, a portion of the dural membrane, the facet joints, the spinal nerve roots and ganglia, and the associated paravertebral muscle fascia. There is no doubt that the facet joint is a potential source of chronic LBP. Facet joints are true synovial joints that have a joint space, hyaline cartilage surfaces, a synovial membrane, and a fibrous capsule. Two medial branches of the dorsal rami innervate the facet joints. If conservative measures fail in the treatment of facet joint pain, pulsed radiofrequency (PRF) of the medial branches can be administered. Objectives:: The aim of this observational study was to evaluate the efficacy of PRF in the treatment of lumbar chronic facet joint pain. Patients and Methods:: In this prospective observational study, we selected 300 patients who suffered from lumbar facet joint pain, were referred to the Pain Therapy Department, and underwent PRF treatment of the lumbar medial branches. We analyzed patients with facet joint pain that was unresponsive to conventional treatment, with a positive response to diagnostic medial branch block, who underwent PRF of the lumbar area for 18 months at San Giovanni Hospital of Rome. Results:: Three hundred patients were eligible for the study. After 1 month, 62% of patients (186 patients) reported good pain relief [95% confidence interval (CI) 0.53, 0.7]; 8.6% (26 patients) reported excellent pain relief (95% CI 0.07-0.09); 20. 4% (61 patients) reported poor pain relief (95% CI 0.18-0.22), and 9% (27 patients) reported no pain relief (95% CI 0.08-0.099). The average pain numeric rating scale (NRS) score before the procedure was 6 (range 4-9), decreasing to 2 after the procedure (range 0-4). SF-36 physical and mental parameters improved significantly after the treatment [≥ 1 standard deviation (SD)]. Results after 6 months were similar to those obtained after 1 month. Conclusions:: This study suggests that PRF treatment of the lumbar medial branches provides good pain relief for at least 6 months in 70% of patients who suffer from lumbar facet joint pain.